Check out this website UFO how to. It is selling books on patents found worldwide on UFO type craft. Website is http://www.ufohowto.com/ .The patents are outdated so you don't need to pay anyone to use the patents. I hope this helps you. According to the author the cost of such craft is not much. Here are some quotations of the cost from the website.
Yet a small, privately-owned flying saucer would cost less than an
automobile to build, would use practically no fuel, would travel thousands
of miles per hour, would last a long time, and would require practically no
William Lyne, author -- "Occult Ether Physics: Tesla's Hidden Space
Propulsion System and the Conspiracy to Conceal It" page 9
"The expense of materials for fabrication of these craft is so insignificant as
to not be an obstacle. Basic automotive wiring is sufficient to meet requirements,
and navigational flight equipment can be retrofitted from any airplane. Ceramics can
be baked from sand from the beach or from any desert; and/or from clay from most
any source, salted with magnesium or any other material with odd nuclear spin values.
The fact is that the materials to build one of these out-of-this-world craft are hidden
in plain sight. There is nothing exotic or extraordinary required, only the facilities to
do the fabrication work in."
Luke Fortune, in a "negotiation correspondence" to ***** Corporation,
[Non-disclosure agreement was signed prohibiting identification of ***** Corp.